Honestly, it’s because this has been one of (if not arguably the single best) marketing campaign video games has seen. It was perfectly announced (and playable the day of announcement), and then followed up with very strategically timed betas and animated shorts. People got emotionally connected to the characters…

The characters are very well designed, with lots of vibrant personality. The “pixar-like” cinematics are also helping the audience to create emotional attachments to them.

Because all the stuff you pay for which are mainly weapon skins used to be entirely free.